To begin, it is first disclosed that it is known to place samples on stages in ellipsometer and the like systems, and to cause a polarized beam of electromagnetic radiation to impinge on said sample at an oblique angle thereto, interact with said sample and then enter a detector. It is also known that the “tilt” of a sample surface at a specific location thereon can affect realized angle and plane of incidence values actually achieved. Further, it is known to adjust the vertical height of the stage to position a sample such that a beam of electromagnetic radiation reflecting therefrom enters a detector.
Continuing, spectrophotometer, reflectometer, polarimeter, ellipsometer and the like systems are known, (eg. Rotating Analyzer, Rotating Polarizer, Rotating Compensator, Modulator Element Ellipsometer), and the like systems (SYS) are known. Typical construction provides of such systems include a Sample Supporting Stage which is substantially fixed in location. Functionally oriented with respect thereto are a Substantially Fixed Position Source Means (S) for providing a beam of electromagnetic radiation at an oblique angle to said Sample Supporting Stage, and a Substantially Fixed Position Data Detector Means (D) for intercepting Electromagnetic Radiation which Reflects (or Transmittes through), a Sample placed on said Sample Supporting Stage. Typical procedure is to place a Sample onto the Sample Supporting Stage, cause a beam of Electromagnetic Radiation to impinge thereonto, and record data produced by the Data Detector Means in response to electromagnetic radiation which enters thereinto, which data is analyzed to provide insight into Sample Optical and Physical properties. Said procedure can include adjustment of the Sample Supporting Stage in an “X”-“Y” Plane, and along a “Z” direction perpendicular to its surface, (ie. a vertical position adjustment where the Electromagnetic Radiation approaches the Sample at an oblique angle from a laterally located Source). This purpose of said adjustment is to, for instance, enable the directing of a beam of Electromagnetic Radiation Reflected from a Sample placed on said Sample Supporting Stage into the Data Detector without moving the Data Detector so it intercepts a beam exiting said Sample. It should be appreciated then that conventional Reflectometer, Spectrophotometer, Ellipsometer and Polarimeter Systems which include provision for such Sample positioning adjustment and orientation with respect to an impinging Electromagnetic beam, typically do so by allowing the Sample Supporting Stage position to be adjusted, rather than by effecting simultaneous change in location of the Source and Data Detector with respect to the Sample Supporting Stage, because it is far simpler to implement Sample Supporting Stage location change.
Continuing, a typical goal in ellipsometry is to obtain, for each wavelength in, and angle of incidence of said beam of electromagnetic radiation caused to interact with a sample system, sample system characterizing PSI and DELTA values, (where PSI is related to a change in a ratio of magnitudes of orthogonal components rp/rs in said beam of electromagnetic radiation, and wherein DELTA is related to a phase shift entered between said orthogonal components rp and rs, caused by interaction with said sample system:TAN(ψ)e(iΔ)=rp/rs 
As indicated above, Ellipsometer Systems generally include a source of a beam of electromagnetic radiation, a Polarizer, which serves to impose a known, (typically linear), state of polarization on a beam of electromagnetic radiation, a Stage for supporting a sample system, and an Analyzer which serves to select a polarization state in a beam of electromagnetic radiation after it has interacted with a material system, and pass it to a Detector System for analysis therein. As well, one or more Compensator(s) can be present and serve to affect a phase retardence between orthogonal components of a polarized beam of electromagnetic radiation. A number of types of ellipsometer systems exist, such as those which include rotating elements and those which include modulation elements. Those including rotating elements include Rotating Polarizer (RP), Rotating Analyzer (RA) and Rotating Compensator (RC). A preferred embodiment is a Rotating Compensator Ellipsometer System because they do not demonstrate “Dead-Spots” where obtaining ellipsometric data is difficult. They can read PSI and DELTA of a Material System over a full Range of Degrees with the only limitation being that if PSI becomes essentially zero (0.0), one can't then determine DELTA as there is not sufficient PSI Polar Vector Length to form the angle between the PSI Vector and an “X” axis. In comparison, Rotating Analyzer and Rotating Polarizer Ellipsometers have “Dead Spots” at DELTA's near 0.0 or 180 Degrees and Modulation Element Ellipsometers also have a “Dead Spot” at PSI near 45 Degrees). The utility of Rotating Compensator Ellipsometer Systems should then be apparent. Another benefit provided by Rotating Compensator Ellipsometer Systems is that the Polarizer (P) and Analyzer (A) positions are fixed, and that provides benefit in that polarization state sensitivity to input and output optics during data acquisition is essentially non-existent. This enables relatively easy use of optic fibers, mirrors, lenses etc. for input/output.
While Data taken at one (AOI) and one or multiple wavelengths is often sufficient to allow ellipsometric characterization of a sample system, the results of Ellipsometric Investigation can be greatly enhanced by using multiple (AOI's) to obtain additional data sets. However, while it is relatively easy to provide Wavelength change without extensive difficult physical Ellipsometer System Orientation change, it is typically difficult to change the Angle-of-Incidence (AOI) that a Beam of Electromagnetic Radiation makes to a surface of a sample system. An (AOI) change requires that both the Source of the Electromagnetic Beam and the Detector must be re-positioned and aligned, and such is tedious and time consuming.
While present invention systems can be applied in any material system investigation system such as Polarimeter, Reflectometer, Spectrophotometer and the like Systems, an important application is in Ellipsometer Systems, whether monochromatic or spectroscopic. It should therefore be understood that Ellipsometry involves acquisition of sample system characterizing data at single or multiple Wavelengths, and at one or more Angle(s)-of-Incidence (AOI) of a Beam of Electromagnetic Radiation to a surface of the sample system. Ellipsometry is generally well described in a great many number of publications, one such publication being a review paper by Collins, titled “Automatic Rotating Element Ellipsometers: Calibration, Operation and Real-Time Applications”, Rev. Sci. Instrum. 61(8) (1990).
It is also noted that Ultraviolet (UV) or Infra-Red (IR) Wavelengths are absorbed by oxygen or water vapor, hence where they are applied, it is necessary to evacuate or purge at least the region around a sample.
Further, it is to be understood that causing a polarized beam of electromagnetic radiation to interact with a sample system generally causes change in the ratio of the intensities of orthogonal components thereof and/or the phase shift between said orthogonal components. The same is generally true for interaction between any system component and a polarized beam of electromagnetic radiation. In recognition of the need to isolate the effects of an investigated sample system from those caused by interaction between a beam of electromagnetic radiation and system components other than said sample system, (to enable accurate characterization of a sample system per se.), this Specification incorporates by reference the regression procedure of U.S. Pat. No. 5,872,630 in that it describes simultaneous evaluation of sample characterizing parameters such as PSI and DELTA, as well system characterizing parameters, and this Specification also incorporates by reference the Vacuum Chamber Window Correction methodology of U.S. Pat. No. 6,034,777 to account for phase shifts entered between orthogonal components of a beam of electromagnetic radiation, by present invention system multiangle prisms and/or lenses.
Another patent which is incorporated hereinto by reference is U.S. Pat. No. 5,969,818 to Johs et al. Said 818 patent describes a Beam Folding Optics System which serves to direct an electromagnetic beam via multiple reflections, without significantly changing the phase angle between orthogonal components therein. Briefly, two pairs of mirrors are oriented to form two orthogonally related planes such that the phase shift entered to an electromagnetic beam by interaction with the first pair of mirrors is canceled by interaction with the second pair.
Another patents incorporated hereinto by reference is U.S. Pat. No. 5,757,494 to Green et al., in which is taught a method for extending the range of Rotating Analyzer/Polarizer ellipsometer systems to allow measurement of DELTA'S near zero (0.0) and one-hundred-eighty (180) degrees. Said patent describes the presence of a window-like variable bi-refringent component which is added to a Rotating Analyzer/Polarizer ellipsometer system, and the application thereof during data acquisition, to enable the identified capability.
A patent to Thompson et al. U.S. Pat. No. 5,706,212 teaches a mathematical regression based double Fourier series ellipsometer calibration procedure for application, primarily, in calibrating ellipsometers system utilized in infrared wavelength range. Bi-refringent window-like compensators are described as present in the system thereof, and discussion of correlation of retardations entered by sequentially adjacent elements which do not rotate with respect to one another during data acquisition is described therein.
A patent to Woollam et al, U.S. Pat. No. 5,582,646 is disclosed as it describes obtaining ellipsometric data through windows in a vacuum chamber, utilizing other than a Brewster Angle of Incidence.
Patent to Woollam et al, U.S. Pat. No. 5,373,359, patent to Johs et al. U.S. Pat. No. 5,666,201 and patent to Green et al., U.S. Pat. No. 5,521,706, and patent to Johs et al., U.S. Pat. No. 5,504,582 are disclosed for general information as they pertain to Rotating Analyzer ellipsometer systems.
Patent to Bernoux et al., U.S. Pat. No. 5,329,357 is identified as it describes the use of optical fibers as input and output means in an ellipsometer system.
A patent to Finarov, U.S. Pat. No. 5,764,365 is disclosed as it describes a system for moving an ellipsometer beam over a large two-dimensional area on the surface of a sample system, which system utilizes beam deflectors.
A patent to Berger et al., U.S. Pat. No. 5,343,293 describes an Ellipsometer which comprises prisms to direct an electromagnetic beam onto a sample system.
A patent to Canino, U.S. Pat. No. 4,672,196 describes a system which allows rotating a sample system to control the angle of incidence of a beam of electromagnetic radiation thereonto. Multiple detectors are present to receive the resulting reflected beams.
A patent to Bjork et al., U.S. Pat. No. 4,647,207 describes an ellipsometer system in which reflecting elements are moved into the path of a beam of electromagnetic radiation.
U.S. Pat. No. 6,081,334 to Grimbergen et al. describes a system for detecting semiconductor end point etching including a means for scanning a beam across the surface of a substrate.
A patent to Ray, U.S. Pat. No. 5,410,409 describes a system for scanning a laser beam across a sample surface.
U.S. Pat. No. 3,874,797 to Kasai describes means for directing a beam of electromagnetic radiation onto the surface of a sample using totally internally reflecting prisms.
U.S. Pat. No. 5,412,473 to Rosencwaig et al., describes a ellipsometer system which simultaneously provides an electromagnetic beam at a sample surface at numerous angles of incidence thereto.
A patent to Chen et al., U.S. Pat. No. 5,581,350 is identified as it describes the application of regression in calibration of ellipsometer systems.
Existing Provisional and Utility applications, (ie. 60/459,690 filed Apr. 3, 2003 and 10/652,696 filed Sep. 2, 2003), by the Inventor herein, show a prior art system for detecting sample tilt, and a system which utilizes an ellipsometer beam reflected from a sample to perform vertical positioning of a stage. A beam splitter is used to divert a portion of the reflected beam into a detector and used to mediate adjustment of the sample's vertical position and/or tilt. While said system does not “lock-in” tilt and relative position of the ellipsometer and sample, it provides for aligning a sample system and controlling the angle and plane of incidence at which a beam of electromagnetic radiation obliquely impinges on a monitored location of a surface of a sample, and comprises, as viewed in side elevation:                a sample supporting stage which can be translated in “X”, “Y” or “Z” directions as well as rotated about “X”, “Y” and optionally “Z” axes;        vertically above said stage there being a first beam splitter means, a lens and a first camera means for providing a view of a portion of the surface of said sample, said first beam splitter means optionally having positioned on a lower surface thereof light emitting means for providing light to the surface of said sample;        laterally with respect to said first beam splitter means there being a reflection means;        vertically above said reflection means there being a second beam splitter;        vertically above said second beam splitter there being a second camera means and laterally with respect to said second beam splitter, there being sequentially a lens and an essentially point source of electromagnetic radiation;        said first and second camera means each having associated therewith display means.        Said system further comprises an ellipsometer polarization state generator to cause, and a polarization stage detector to monitor, a beam of electromagnetic radiation which in use impinges on said monitored location on said surface of said sample at an oblique angle thereto.        In use said first camera means and its associated display means provide a view of at least a portion of the surface of a sample utilizing light provided by said light emitting means for providing light to the surface of said sample positioned on said lower surface of said first beam splitter, and said essentially point source of electromagnetic radiation provides electromagnetic radiation to the surface of said sample via said second beam splitter, said reflective means and said first beam splitter, and said sample supporting stage is caused to be translated in any of said “X”, “Y” and “Z” directions as well as rotated about said “X”, “Y” and optionally “Z” axes which are necessary to cause an interrogating beam of electromagnetic radiation provided by said essentially point source of a source of electromagnetic radiation to reflect from the surface of said sample, proceed back through said first beam splitter means, reflect from said reflective means, pass through said second beam splitter means, enter said second camera means and cause an image on the display means associated therewith which indicates that the monitored location on the sample surface is oriented so as to face substantially vertically.        The purpose of the foregoing is to align said sample surface to assure that said beam of electromagnetic radiation provided to said monitored location on the surface of said sample at an oblique angle approaches said surface at known intended angle of incidence and plane of incidence orientation, rather than at an angle of incidence and plane of incidence orientation which is modified by surface irregularities or non-flat samples.Said system can further comprise a polarizer means in the path of said beam of electromagnetic radiation provided by said essentially point source of electromagnetic radiation, and in which said first beam splitter is sensitive to polarization state, and the polarizer means can be adjustable to enable control of the direction of polarization. The system point source of a source of electromagnetic radiation can comprise a fiber optic.        
A patent to Abraham et al., U.S. Pat. No. 6,091,499 describes a method and system for automatic relative adjustment of samples in relation to an ellipsometer. Paraphrasing, said Abraham et al. system basically comprises:                a system for orienting a sample on a stage in an ellipsometer system comprising a first light source, a polarizer, said stage, an analyzer and a detector;        said system further comprising a detection system having a second light source, wherein said detection system is independently adjustable in relation to said ellipsometer, and wherein said detection system can be electronically locked into position relative to said ellipsometer so that said ellipsometer and said detection system can be adjusted as one unit in relationship to said stage, wherein said detection system can detect both a tilt of a sample placed onto said stage, and a distance of said sample from a coordinate source of the ellipsometer in two perpendicular axes; and        said system further comprising an adjusting device, wherein said adjusting device can adjust tilt of said stage, and        wherein said adjusting device can adjust the position of said ellipsometer and detection system when in an electronically locked relationship with respect to one another.        
Additional known patents are:                Patent to Coates U.S. Pat. No. 4,373,817;        Patent to Coates U.S. Pat. No. 5,045,704;        RE. 34,783 to Coates;        Patent to Mikkelsen et al., U.S. Pat. No. 6,600,560;        Patent to Fanton et al., U.S. Pat. No. 5,596,411;        Patent to Piwonka-Corle et al., U.S. Pat. No. 5,910,842;        Patent to Piwonka-Corle et al., U.S. Pat. No. 5,608,526;        Patent to Bareket, U.S. Pat. No. 5,889,593;        Patent to Norton et al., U.S. Pat. No. 5,486,701;        Patent to Aspnes et al., U.S. Pat. No. 5,900,939;        PCT Application Publication WO 99/45340;        Published Application of Stehle et al., No. US2002/0024668 A1.        
While the above patents describe various methodology, none disclose a method of aligning an ellipsometer system which comprises:                an ellipsometer source of a beam of electromagnetic radiation;        a stage for supporting a sample and having means for effecting tip/tilt and translation thereof;        a data detector of electromagnetic radiation;and which method comprises:        
a) placing an alignment sample on said stage;
b) generally orienting said ellipsometer source of a beam of electromagnetic radiation so that it directs a beam of electromagnetic radiation onto a first location of said alignment sample at an oblique angle, which beam then reflects from said alignment sample and enters said data detector so that it provides an output signal;
itteratively repeating steps in any functional order until the output of the data or alignment detector is substantially the same when the stage is caused to effect translation of said alignment sample so that said beam is directed to a second or third or fourth location thereon at said oblique angle, reflects therefrom and enters said data detector, followed by adjusting the tip/tilt of said stage with the result being that the stage is oriented in tip/tilt so that no matter from what location on said alignment sample said beam is caused to reflect, the output from said data detector remains substantially the same;said method then optionally further comprising:
d) while monitoring the data detector or alignment output signal moving the location and orientation thereof until said output signal therefrom is substantially maximized.
Need remains for additional systems and methods for orienting the vertical position, and tilt, of samples in ellipsometer, polarimeter, spectrophotometer and the like systems.